@jax,
Just a word of advice, don't expect quick answers on the weekends. There aren't a lot of classic drivers on AO to start with, and most of us don't seem to hang around here on Saturdays and Sundays.
Now personally I have no clue what you mean by rear wing. I thought only the front fenders were "wings." I've never had to deal with S3 or S4 quarter panels

but I'd guess just by looking at the cars that the sheet metal is different in every major body style.
And yes, all the square-tailed spiders are Kamm tails. See the Spider S2 section at
http://www.alfaclassico.com/ for fuller details.
--Toronto